Compact height torque sensing articulation axis assembly

ABSTRACT

A compact height torque sensing articulation axis assembly is disclosed herein having a torque sensor, an assembly mounting flange, a motor, a motor gearbox, a gearbox output shaft, an encoder, and a cable. The assembly may sense tension on robotic catheter pullwires in an articulating catheter and/or torque on a robotic output axis using the torque sensor. Disclosed embodiments may advantageously be used to achieve small, lightweight robotic catheter systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application62/329,617, filed Apr. 29, 2016, the entirety of which is herebyincorporated by reference herein for any and all purposes as if setforth herein in its entirety. Embodiments described in this applicationmay be used in combination or conjunction with the subject matterdescribed in one or more of the following, each of which is hereby fullyincorporated by reference for any and all purposes as if set forthherein in their entireties:

U.S. patent application Ser. No. 13/835,136, filed Mar. 15, 2013,entitled “ACTIVE DRIVE MECHANISM FOR SIMULTANEOUS ROTATION ANDTRANSLATION;”

U.S. patent application Ser. No. 13/839,967, filed Mar. 15, 2013,entitled “VASCULAR REMOTE CATHETER MANIPULATOR;”

U.S. patent spplication Ser. No. 14/214,711, filed Mar. 14, 2013,entitled “CATHETER TENSION SENSING;” and

U.S. Pat. No. 9,173,713, issued Nov. 3, 2015, entitled “TORQUE-BASEDCATHETER ARTICULATION.”

BACKGROUND

Robotic surgical systems and devices are well suited for use inperforming minimally invasive medical procedures. For example, a roboticsurgical system may be utilized to facilitate imaging, diagnosis, andtreatment of tissues and vessels which may lie deep within a patient,and which may be preferably accessed only via naturally-occurringpathways such as blood vessels or the gastrointestinal tract.

One such robotic surgical system that may be utilized in a minimallyinvasive procedure is a robotic catheter system. A robotic cathetersystem utilizes a robot, external to the patient's body cavity, toinsert a catheter through a small incision in a patient's body cavityand guide the catheter to a location of interest. Catheters may besteerable for movement in multiple axes, including axial translation(i.e., insertion and retraction), axial rotation, anddeflection/articulation (including radial bending in multipledirections). To accomplish steering, one or more pullwires are attachedto a distal articulating section of a catheter and extend through thecatheter to at least the catheter's proximal end. The distal tip of thecatheter may then be controlled via the pullwires (e.g., by selectivelyoperating tensioning control elements, which control tension and/ordisplacement of the pullwires within the catheter instrument).

Kinematic modeling is utilized to predict catheter tip movement withinthe patient anatomy. The amount of displacement of a pullwire isgenerally proportional to the amount of articulation, enabling modelingof predicted catheter tip movement. However, at times, pullwiredisplacement may not result in the expected catheter tip articulation.Various elements can affect the amount of articulation for a givenpullwire actuation, including the presence of unanticipated orun-modeled constraints imposed by the patient's anatomy, particularlygiven the tortuous path that the catheter must traverse. Additionally,pullwire displacement may result in an increase in pullwire tensionrather than a change in catheter articulation if there is undetectedslack in the pullwire. When unanticipated and un-modeled conditions orconstraints exist, kinematic modeling may not accurately predictcatheter tip movement leading to errors. Minimization of differencesbetween actual and predicted kinematic functions is thus desirable toachieve a highly controllable robotic surgical system.

In robotic catheter systems, output shafts that actuate the pullwiresconnect the transmission elements in the catheter (e.g., pullwires) tomotors in the robotic system. For the reasons discussed above, detectingload and/or torque on the output shafts as well as monitoring andcontrolling pullwire displacement may more accurately predict cathetertip movement than monitoring pullwire displacement alone.

Currently, some examples of robotic catheter systems are equipped with arotary or shaft encoder. While the rotational position of the outputshaft may be determined from the encoder, the torque applied at theoutput shaft may not be able to be precisely calculated because ofvariations in transmission efficiency and the effects of perturbationson the system due to catheter construction shape and use. Moreover, theencoder may not provide accurate information on load. For example,external forces on the catheter can change the loading on the catheterpullwires and, for a fixed position of the output shaft, in turn maychange the torsion loading on the output shafts. As such, a need existsfor improved load and/or torque sensing on the output shaft.

Another example of a robotic catheter system that utilizes a robot,external to the patient's body cavity, to insert and retract cathetersand guidewires through a small incision in a patient's body cavity andguides the catheters/wires to a location of interest is described inU.S. application Ser. Nos. 13/835,136 and 13/839,967 (previouslyincorporated by reference). To accomplish linear translation (i.e.,insertion and/or retraction) of the catheter or guidewire, this roboticcatheter system uses a set of motors to rotate opposing wheels orrollers in opposite directions. In this system, the motors rotate tocontrol the rate of linear translation. The angular rotation of theroller may be used to control the linear displacement of the catheter orguidewire. In other words, the linear travel of the catheter or wire isgenerally proportional to the angular rotation of the rollers. However,if higher insertion forces are encountered, the catheters or guidewiresmay slip between the rollers and not be inserted as far as intended.Some robotic systems incorporate torque sensors on the motors to measurethe torque required to insert the catheter or guidewire.

In many robotic catheter systems, steering of the catheter is controlledby an instrument driver. The instrument driver may contain, for example,the one or more motors that drive the one or more output shafts. Thereis a need to keep the instrument driver of the robotic catheter systemsmall so that it does not interfere with the available workspace in asurgical suite or catheterization lab. There are size constraints on alldimensions of the instrument driver. If the instrument driver of asurgical system is too wide, then it will obscure certain parts of theanatomy for an external imaging source such as a fluoroscopy system. Ifthe instrument driver is too long, then the carriages cannot come closeenough together on telescoping robotic systems, and the inner cathetercannot be inserted as far into the outer catheter, resulting in a needfor longer catheters and a lack of control. If the instrument driver istoo tall, then the angle of entry into the patient becomes too steep,resulting in access site injuries such as bleeding or hematomas.

A robotic vascular catheter system typically includes elongate membersthat include a sheath catheter, a leader catheter, and a guidewire. Moregenerally, a robotic system for driving an elongate member into apatient lumen typically includes an outer elongate member, an innerelongate member, and a guidewire. Each is separately controllable andmay telescope with respect to one another. For instance, a sheathcarriage controls operation of the sheath (or outer elongate member) andis moveable along a generally axial direction aligned axially with thepatient (referred to herein as the insertion axis), and a leadercarriage controls operation of the leader (or inner elongate member) anda guidewire and is likewise moveable about the insertion axis of thepatient. Typically, the leader carriage and the sheath carriage arepositioned on an instrument driver often referred to as a remotecatheter manipulator (RCM), which is supported by a setup joint (SUJ).Because the sheath carriage and leader carriage are traditionallyaligned along the insertion axis, this configuration results in the RCMtaking up significant space over the patient. If the RCM is too large,the system can interfere with other system operations (such as operationof the C-arm and/or monitors).

For instance, in some minimally-invasive surgery procedures, an imagingdevice such as a fluoroscopy system may be required in addition to theRCM. In such procedures, the imaging device may scan and image theentire body from the insertion site to the site of the medicalprocedure. If the RCM is too large, the RCM may obstruct the imagingdevice's ability to capture the entire desired imaging field.

Accordingly, despite the benefits of torque sensing, many roboticcatheter systems do not have torque sensing due to the size constraintsmentioned here. Therefore, there remains a need for a compact torquesensor that can provide the torque information needed to better controlthe catheter without increasing the size of the instrument driver.

SUMMARY

In some embodiments, a robotic surgical system may include a controlsystem electrically connectable to an input device and configured toreceive information for positioning or orienting a catheter from theinput device; the system may further include an instrument driveroperatively connected to the control system. The instrument driver mayinclude one or more articulation drive assemblies. Each articulationdrive assembly may include: a motor configured to provide rotary outputto actuate movement of an elongate member or other component of thesurgical system; a gearbox configured to modify the rotary output of themotor; and a reactive torque sensor coaxial with and radiallysurrounding at least a portion of the rotary output motor and/or thegearbox. The motor may be at least partially within the reactive torquesensor to minimize height of the articulation drive assembly. Thecontrol system may be configured to actuate the motor in response to theinformation, from the input device, to drive an output shaft incommunication with the elongate member. The instrument driver may beconfigured to determine an output shaft torque imparted by the outputshaft to the elongate member. The reactive torque sensor may be coaxialwith, and at least partially radially surround, both the rotary outputmotor and the gearbox. At least one of the gearbox and the motor may bemounted to the reactive torque sensor by a first mounting flange. Thearticulation drive assembly may be mounted to the instrument driverhousing by the second mounting flange of the torque sensor. The firstand second flanges may be configured to ground torque loads. Thereactive torque sensor may further include at least one load cellconfigured to measure the output shaft torque. The articulation driveassembly may be configured to adjust a pullwire tension to impart motionto a tip of a catheter or elongate device or alternatively may beconfigured to rotate a drive wheel or roller on an active drive deviceto insert, retract, or rotate an elongate device. The system may furtherinclude a motor cable wrapped at least once around and communicativelycoupled to at least one of the motor, the gearbox, and the torquesensor. The cable may be clock spring wound.

In some embodiments, an instrument driver for an elongate member of arobotic surgical system may include: a gearbox configured to actuatemovement of the elongate member by driving an output shaft incommunication with the elongate member; a rotary output motoraxially-aligned with the gearbox and configured to drive the gearbox;and a reactive torque sensor radially surrounding the gearbox andconfigured to determine an output shaft torque imparted by the outputshaft to the elongate member. The reactive torque sensor may provide agrounded mounting structure for the motor and gearbox. The reactivetorque sensor may have a length shorter than the combined length of themotor and gearbox. The reactive torque sensor may have a length shorterthan the gearbox. The rotary output motor may be a brushless low-profileoutrunner motor. The instrument driver may further include aclock-spring style wound flat flex cable assembly configured to providean electrical connection to the motor.

A method of measuring an output torque may include providing a rotaryoutput shaft configured to actuate an elongate member, providing atleast one output motor configured to actuate movement of the elongatemember by driving the output shaft, and determining an output torque ofthe output shaft using a torque sensor disposed in surrounding relationto the motor. The method may further include establishing the sensorinput as a reactive torque sensor input, the reactive torque sensorinput measured via a connection between the reactive torque sensor andthe motor. The method may further include providing a gearbox coupled tothe motor. The method may further include modifying the output torque bysending a signal to the motor. The signal may be sent to the motor overa clock-spring style wound flat flex cable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary robotic surgical system.

FIG. 2 is a perspective view of an exemplary catheter assembly of thesurgical system of FIG. 1.

FIG. 3 is a schematic showing a kinematic relationship between pullwiredisplacement and catheter tip articulation.

FIG. 4 is a partially-exploded view of the catheter assembly of FIG. 2.

FIG. 5 is a partially-exploded view of the catheter assembly of FIG. 2.

FIG. 6 is a perspective view of an exemplary steerable catheter withpullwires.

FIG. 7 is a perspective view of a compact height torque sensingarticulation drive assembly system, according to an exemplaryillustration.

FIG. 8 is a perspective view of a compact height torque sensingarticulation drive assembly system, including indications of motorrotation direction, torque resisting load, and an axis, according to anexemplary illustration.

FIG. 9 is a bottom view of a compact height torque sensing articulationdrive assembly system, according to an exemplary illustration.

FIG. 10 is a top view of a compact height torque sensing articulationdrive assembly system, according to an exemplary illustration.

FIG. 11 is a cross section view of a compact height torque sensingarticulation drive assembly system, according to an exemplaryillustration.

FIG. 12 is a cutaway view of a compact height torque sensingarticulation drive assembly system, according to an exemplaryillustration.

FIG. 13 is an exploded view of a compact height torque sensingarticulation drive assembly system, according to an exemplaryillustration.

FIGS. 14A and 14B are perspective views of torque sensors showing theposition of strain gauges, according to exemplary illustrations.

FIGS. 15A-15C are side views of configurations of struts of a torquesensor, according to exemplary illustrations.

FIGS. 16A-16C are cutaway views of arrangements between a torque sensor,a motor, a gearbox, a grounded structure, and an output shaft, accordingto exemplary illustrations.

FIGS. 17A-17C are cutaway views of configurations of a torque sensor, amotor/gearbox, a grounded structure, and an output shaft, according toexemplary illustrations.

FIG. 18 is a process flow diagram for an exemplary method of measuringan output torque.

DETAILED DESCRIPTION

Referring now to the discussion that follows and also to the drawings,illustrative approaches to the disclosed assemblies are shown in detail.Although the drawings represent some possible approaches, the drawingsare not necessarily to scale and certain features may be exaggerated,removed, or partially sectioned to better illustrate and explain thepresent disclosure. Further, the descriptions set forth herein are notintended to be exhaustive or otherwise limit or restrict the claims tothe precise forms and configurations shown in the drawings and disclosedin the following detailed description.

As used herein, the term “catheter” may refer to any flexible elongatemedical instrument.

Referring to FIG. 1, a robotic surgical system 100 is illustrated inwhich an apparatus, a system, and/or method may be implemented accordingto various exemplary illustrations. The system 100 may include a roboticcatheter assembly 102 having one or more elongate members such as asheath instrument 104 and/or a catheter instrument 106. The catheterassembly 102 and the sheath instrument 104 are controllable using arobotic instrument driver (or drivers) 108 (generally referred to as“instrument driver”). During use, a patient is positioned on anoperating table or surgical bed 110 to which the robotic instrumentdriver 108 is coupled or mounted. In the illustrated example, the system100 includes an operator workstation 112, an electronics rack 114including a control computer (not shown), a setup joint mounting brace116, and instrument driver 108. A surgeon is seated at the operatorworkstation 112 and can monitor the surgical procedure, patient vitals,and control one or more catheter devices.

The operator workstation 112 may include a computer monitor to displayan object, such as a catheter displayed within or relative to a bodycavity or organ (e.g., a chamber of a patient's heart). In one example,an operator uses one or more input devices 120 to control the positionof a catheter or other elongate instrument. In response to actuation ofthe input device by a user, the input device can output information forthe desired position or orientation of the elongate instrument,including the three-dimensional spatial position and/or orientation ofthe distal end of a steerable elongate instrument. System components,including the operator workstation, electronics rack and the instrumentdriver, may be coupled together via a plurality of cables or othersuitable connectors 118 to provide for data communication, or one ormore components may be equipped with wireless communication componentsto reduce or eliminate cables 118. Communication between components mayalso be implemented over a network or over the internet. In this manner,a surgeon or other operator may control a surgical instrument whilelocated away from or remotely from radiation sources. Because of theoption for wireless or networked operation, the surgeon may even belocated remotely from the patient in a different room or building.

The operator workstation 112, the electronic rack 114 and/or theinstrument driver can form part of a control system 113. As will beexplained below, the control system 113 can be configured to actuate amotor within the instrument driver 108 in response to information fromthe one or more input devices 120 and/or the instrument driver to drivean output shaft that can be used to control movement of one or moreelongated members such as a sheath instrument 104 and/or an catheterinstrument 106. The control system 113 can reside in one or more of theoperator workstation 112, the electronic rack 114 and/or the instrumentdriver and/or in other components.

Referring now to FIG. 2, motors within instrument driver 108 arecontrolled such that carriages coupled to mounting plates 204, 206 aredriven forwards and backwards on bearings. As a result, one or moreelongate instruments can be controllably manipulated while inserted intothe patient or retracted out of the patient. The instrument driver 108contains motors that may be activated to control bending of the one ormore elongate instruments as well as the orientation of the distal tips,and optionally, tools mounted at the distal tips.

The articulation of catheters is normally performed by actuatingpullwires that extend the length of the catheter and are attached to anarticulating section of a catheter at or near the catheter's distal end.In order to articulate the catheter, the pullwire is manipulated anddisplaced at the proximal end to articulate the distal end of thecatheter. Typically, the amount that an articulating section of acatheter articulates is determined by calculating the change in pathlength that an actuating pullwire takes. For a straight catheter, thatlength is equal to the articulating section, L₀. As the catheter bends(where a is the angle from the neutral axis, r_(c) is the radius of thecatheter, and τ is the articulation angle), the path length is equal toL₀−cos (α/90)*r_(c)*τ. The difference—(α/90)*r_(c)*τ—is the distance thepullwire must be actuated to make a catheter articulate to an angle τ,as illustrated in FIG. 3. From this concept, further solid mechanic andkinematic modeling is used via algorithms in the control computer toconvert a desired catheter position or orientation as provided by theuser into commands to the instrument driver to rotate motors designatedfor each pullwire.

In order to prepare a catheter to be manipulated and articulated by aninstrument driver, the catheter is mounted to the instrument driver.More particularly, the catheter is provided with a splayer, which ismounted onto an interface plate. In some embodiments, as shown in FIG.4, a sheath splayer 308 is placed onto a sheath interface plate 206 anda guide splayer 306 is placed onto a guide interface plate 204. In theillustrated example, each interface plate 204, 206 has respectively fouropenings 310, 312 that are designed to receive corresponding driveshafts 314, 316 (FIG. 5 illustrates an underside perspective view ofshafts 314, 316) attached to and extending from pulley assemblies of thesplayers 308, 306. The drive shafts 314, 316 are each coupled to arespective motor within the instrument driver 108 (see, e.g., FIG. 2).

Embodiments with less or more than four pullwires are contemplated bythe present disclosure. When, for example, a four-wire catheter 304 iscoupled to the instrument driver 108, each drive shaft 316 thereof isthereby coupled to a different respective wire 504-510 (see FIG. 6). Assuch, a distal articulation section 512 of the catheter 304 can bearticulated and steered by selectively tightening and looseningpullwires 504-510. Typically, the amount of loosening and tightening isslight, relative to the overall length of the catheter 304. That is,each wire 504-510 typically need not be tightened or loosened more thanperhaps a few centimeters. As such, the motor shafts that tighten/looseneach wire typically do not rotate more than, for example, ¾ of arotation. Thus, given the solid mechanics and kinematics of directingthe instrument driver, a catheter (or other flexible elongateinstrument) may be controlled in an open-loop manner, in which the shapeconfiguration command comes into the beam mechanics and is translated tobeam moments and forces, then translated into pullwire tensions as anintermediate value before finally being translated into pullwiredisplacement given the entire deformed geometry. Based on the pullwiredisplacement command, a motor servo can apply the appropriate electricalcurrent to produce the amount of rotation required to displace thepullwire.

Robotic systems use these algorithms to determine the displacement ofthe pullwires to achieve the desired articulation of a catheter.However, differences between predicted and actual catheter position canresult from the reliance by the kinematic model on certain assumptionsand the lack of certain information. With rigid kinematics, simplegeometry can be used to predict the location of any point along therigid object given the following information: (1) a reference coordinatesystem; (2) an origin, or point in any coordinate system attached to theobject; and (3) an orientation in any coordinate system attached to theobject. Even with rigid structures, external forces, even gravity, maydisrupt the ability to solve the location equation given the informationabove. If the above information is not sufficient to accurately describethe position of one point of an object from another point on the sameobject, then additional information must be provided, like the weight ofthe object, the forces acting on the object, the strength of the object,etc.

Standard equations and constants, like Poisson's ratio, Hertzianstresses, Modulus of Elasticity, and linear stress/strain equations canimprove on the kinematic model but these methods break down once thestrains exceed the standard elastic range (usually about 3%). Forexample, a slim bar may be straight under no distal loading and theequations to predict the location of the distal end are fairlyeffective. However, when a load is placed on the beam, the distal endwill deflect, or strain under the load. Even in a purely elasticresponse to the load, the location or orientation of the distal end ofthe beam is impossible to predict without knowing the magnitude, thedirection, and the location of the external load. Similarly, flexibleinstruments such as catheters with low strength can be deflected byunknown loads at unknown locations and in unknown directions. Yet,prediction of the location and orientation of the distal end of acatheter is an important aspect of a robotic catheter system. Theorientation of the distal end of the catheter based on informationmeasured at the proximal end can better be determined throughembodiments of the present disclosure.

The exemplary illustrations herein may be applicable to a variety ofideas for effectively measuring tension in catheter pullwires, tensionin pullwires in other surgical instruments and/or tension in componentsof other surgical or endoscopic instruments. Tension sensing may be usedto enable or improve pretensioning, catheter control, slack wiremanagement, catheter failure detection, etc., (e.g., as discussed inU.S. Pat. No. 9,173,713, previously incorporated by reference). Thespecific concepts presented herein may be applicable to techniques forobtaining torque measurements on output shafts of an instrument driver.Each will be addressed in further detail below.

FIGS. 7-13 illustrate embodiments of compact height torque sensingarticulation drive assemblies 614, including a torque sensor 616 withmounting flanges 618, struts 619, a motor 620, a motor gearbox 622, agearbox output shaft 624, an encoder 626, and a cable 628. The assembly614 may be aligned along an axis 629 (see, e.g., FIG. 8). For example,the motor 620 and the gearbox 622 may be aligned end-to-end along theaxis 629. The assembly 614 may sense tension on catheter pullwires in anarticulating catheter or torque on a robotic output axis, which cancorrespond to the axis 629 shown in FIG. 8, using the torque sensor 616.In some embodiments, the assembly 614 may sense tension on catheterpullwires in an articulating catheter by sensing and/or determining theoutput torque (also referred to as output shaft torque) produced by theoutput shaft 624 along the robotic output axis 629 using the torquesensor 616. With reference to FIG. 8, the output shaft torque can be ina direction opposite to the torque resisting load applied to the outputshaft 624. The output shaft 624, in some arrangements, can correspond toor be operatively coupled to drive shafts such as the drive shafts 314,316 described above and/or other components.

The torque sensor 616 may be a component of the assembly configured tomeasure torque, and may act as a sensed mounting structure or load cell.It may be configured as a reactive torque sensor that measures torqueinduced strain using one or more self-contained strain gauges to createa load cell. The torque sensor 616 and components thereof may beconfigured to be communicatively coupled to another component or part ofa system, such as the control system 113, in order to transmit and/orreceive signals, such as a measured torque reading. For example, asexplained further below, in some embodiments, the output torque producedby the motor 620 and/or gearbox 622 about the axis 619 can be measuredor determined from a reaction torque required to prevent the motor 620and/or gearbox 622 from turning. Advantageously, the use of a reactivetorque sensor 616 may eliminate the need for a rotary signaltransmission method, thereby reducing complexity and cost of the overallassembly 614. Advantageously, the use of the reactive torque sensor 616according to certain embodiments described herein can result in aparticularly compact torque sensor arrangement that can provide torqueinformation to control a device used with an instrument driver withoutincreasing the size or only minimally increasing the size of theinstrument driver.

For clarity of description, as used herein, the terms “torque sensor,”“reactive torque sensor,” and “reaction torque sensor” interchangeablyrefer broadly, without limitation, to a device that converts a torsionalmechanical input into an output such as an electrical signal and can beused to measure torque.

FIGS. 14A and 14B illustrate embodiments of torque sensors 616 showingexample positions of strain gauges 621. The strain gauges 621 of thetorque sensor 616 may be disposed in various locations on the struts 619of the torque sensor 616. For example, strain gauges 621 may be placedon a side of the strut 619 to detect bending strain (see, e.g., FIG.14A). In another example, the strain gauges 621 may be disposed on acircumferential face of struts 619 to detect shear strain (see, e.g.,FIG. 14B). Strain gauges 621 may also be placed in several differentlocations on a strut to take several measurements. Depending onlocation, the strain gauges 621 may measure shear, compressive and/ortensile loads on the faces of the mounting structure and hence measurethe induced torque on the structure.

FIG. 14A illustrates an embodiment of a torque sensor 616 having fourstrain gauges 621 mounted on a side wall of a strut 619. Thisconfiguration of the torque sensor 616 may be described as a bendingstrain gauge. FIG. 14B illustrates an embodiment of a torque sensor 616having strain gauges 621 arranged in a zig-zag pattern on acircumferential face of a strut 619 of the torque sensor 616 such thatloading of the torque sensor 616 causes stretching of the strain gauge621 and an increased resistance across it. This arrangement may bedescribed as a shear strain gauge sensor. In some embodiments, there maybe strain gauges 621 mounted in a group of four to form a fullWheatstone bridge which ensures strain measurements are temperaturecompensated.

In some embodiments, the sensor 616 with integrated strain gauges 621may be a flexure-based structure. In some embodiments, the torque sensor616 may include mounting flanges 618 connected by struts 619 to createthe flexure based structure. In some embodiments, the strain gauges 621are attached to the struts 619 of the structure to ensure the strain isdetected by a strain gauge 621. The length and thickness of the struts619 of the flexure-based structure may be designed to allow a Wheatstonebridge or a strain gauge to sense torque-induced strain.

FIGS. 15A-15C illustrate several non-limiting examples of configurationsfor struts 619 of the torque sensor 616. FIG. 15A illustrates anembodiment of a torque sensor 616 having an arcuate strut 619. FIG. 15Billustrates an embodiment of a torque sensor 616 having a beam strut 619shaped substantially like a dumbbell or serif “I”. FIG. 15C illustratesan embodiment of a torque sensor 616 having a substantially annularstrut 619. While FIGS. 15A-15C show various example strut shapes for atorque sensor, others are also possible. The strut shapes may beselected to optimize deformation and torque measurement.

The torque sensor 616 may be hollow, have an inner lumen, or beotherwise configured to be disposed around the motor 620, gearbox 622,and/or encoder 626. In one embodiment, the torque sensor may form a ringaround the motor 620, gearbox 622, and/or encoder 626. The torque sensor616 may partially or completely radially surround and be coaxial with aportion of or the entirety of the motor 620, the gearbox 622, and/or thegearbox output shaft 624. For example, the torque sensor 616 may definean opening 617 (see FIG. 13) that is sized and shaped to accommodate themotor 620, the gearbox 622, and/or the gearbox output shaft 624. Theopening 617 may have a diameter or diagonal greater than a diameter or adiagonal of the motor 620 and/or the gearbox 622, such that the motor620 and/or the gearbox 622 fit within the opening 617. The torque sensor616 may be custom designed to fit in surrounding relation to the gearboxand/or motor. Advantageously, this configuration may have significantlylower height (e.g., at least 20% less height) than traditionalarrangements. Accordingly, such a configuration facilitates the additionof torque sensing to articulation drive assemblies without adding anyaxial length to the assembly.

The assembly 614 may be configured such that the torque sensor 616 doesnot add any overall length to the assembly 614 along the axis 629. Forexample, the length of the assembly 614 along the axis 629 is the samelength with or without the torque sensor 616. Some embodiments may beconfigured such that the torque sensor 616 does not add any overalllength to the combined length of the motor 620 and the gearbox 622, suchthat the length of the motor 620 and the gearbox 622 combined is thesame with or without the torque sensor 616. In some embodiments, thetorque sensor 616 is shorter in length than the motor 620 and/or gearbox622. In some embodiments, the torque sensor 616 is sized and shaped suchthat the motor 620, gearbox 622, and/or gearbox output shaft 624 do notextend radially beyond the torque sensor 616. The torque sensor 616 maycircumscribe the motor 620 and/or the gearbox 622.

The torque sensor 616 may be configured to provide a main groundedmounting structure for the motor 620, the gearbox 622, and/or theencoder 626, which may otherwise be suspended and free floating. Forexample, one or more of the motor 620, the gearbox 622, and the encoder626 may be mounted to the torque sensor 616 using one or more mountingflanges 618 or other component. The mounting flanges 618 may have anysuitable shape and structure that facilitates mounting or attachment ofthe torque sensor 616 to another component. The mounting flanges 618 mayinclude an upper flange and a lower flange. In some embodiments, themounting flanges may form a ring. The upper flange may be a flange thatis closer to the output shaft 624 than a lower flange. In someembodiments, a flange (e.g., the lower flange) may be mounted to themotor 620 and/or the gearbox 622. In some embodiments, a flange (e.g.,the upper flange) or another part of the torque sensor 616 may groundtorque loads by attaching to an instrument driver housing or anothergrounded structure. For example, a flange may be grounded to the chassisof an instrument. Thus, in some embodiments, the torque produced by themotor 620 and/or gear box 622 about the axis 619 (see FIG. 8) can bemeasured to determine the reaction torque required to prevent the motor620 and/or gearbox from turning 620. Thus, torque loads can be groundedby coupling a flange (e.g., the upper flange) to a grounded structurewhile the other flange (e.g., the lower flange) can be coupled to themotor 620 and/or gearbox 620. Torque induced strain along the torquesensor 616 can be measured by the strain gauges 621 to measure ordetermine the reaction torque which can be used to measure or determineoutput torque of the motor 620. The output torque can be used, forexample, to determine tension in catheter pullwires in an articulatingcatheter and/or in other components of a robotic surgical system (e.g.,the robotic surgical system 100). In some embodiments, the measured ordetermined output torque can be used by the control system 113 or othercomponent to measure or determine tension in catheter pullwires, tensionin pullwires of other surgical instruments and/or tension in ofcomponents of other surgical or endoscopic instruments. The controlsystem 113 or other components can also use this information to enableor improve pretensioning, catheter control, slack wire management,catheter failure detection, etc.

FIGS. 16A-16C illustrate several non-limiting embodiments ofarrangements between a torque sensor 616, a motor 620, a gearbox 622, agrounded structure 623, and an output shaft 624. In particular, FIG. 16Aillustrates an embodiment having a motor/gearbox 620/622 mounted below agrounded structure 623 via a torque sensor 616 mounted approximately ata mid-point of the motor/gearbox 620/622 with the output shaft extendingbeyond the grounded structure 623. The top of the motor/gearbox 620/622is approximately flush with a top portion of the grounded structure 623.FIG. 16B illustrates an embodiment having a motor/gearbox 620/622mounted below a grounded structure 623 via a torque sensor 616 mountedapproximately at a base of the motor/gearbox 620/622. The top of themotor/gearbox 620/622 is below the grounded structure 623 with theoutput shaft 624 extending beyond the grounded structure 623. FIG. 16Cillustrates an embodiment having a motor/gearbox 620/622 mounted above agrounded structure 623 via a torque sensor 616 mounted at an upperportion of the motor/gearbox 620/622. While FIGS. 16A-16C show variousexample arrangements, others are also possible.

In some embodiments, the motor 620 may be a brushless low-profileoutrunner motor 620; however, other kinds of motors may be used. In someembodiments, the gearbox 622 may be configured to increase torque anddecrease rotational speed that is output from the motor 620, but otherconfigurations may also be used. The output shaft 624 may be directly orindirectly connected to a component of a system to be driven (e.g., anelongate member). The encoder 626 may be any kind of measurement deviceconfigured to measure the rotational movement of one or more components.The encoder 626 may be an optical encoder, a magnetic encoder, or otherkind of encoder. The cable 628 may be a cable for transmitting energy orsignals and may be communicatively coupled to one or more of the torquesensor 616, the motor 620, the gearbox 622, the encoder 626 and/or othercomponents. The cable 628 may be configured as a clock spring wound flatflex cable, which may minimize the torsional resistance that motor leadswould normally produce. The cable may also be configured as a differentkind of wrapped or other cabling system. The wound or wrappedconfiguration of the cable 628 may increase the usable resolution of thetorque sensor 616. The cable 628 may be axially aligned with andsurround or partially surround the torque sensor 616, motor 620, andgearbox 622.

While the various components of the assembly 614 have been illustratedas separate components, they need not be. For example, the gear box 622may be incorporated into the motor 620. As another example, the torquesensor 616 need not be a separate apparatus. It may be integrated into awall of the gearbox or motor, into a housing or grounded plane 623,and/or into another structure.

FIGS. 17A-17C illustrate several non-limiting configurations of a torquesensor 616, a motor/gearbox 620/622, a grounded structure 623, and anoutput shaft 624. In particular, FIG. 17A illustrates an embodimentwherein the torque sensor 616 is integrated into a wall of thegearbox/motor 620/622 and mounted to the grounded structure 623. FIG.17B illustrates an embodiment where the torque sensor 616 is integratedinto the grounded structure 623 and mounted to the motor/gearbox620/622. FIG. 17C illustrates an embodiment where the torque sensor 616,the motor/gearbox 620/622, and the grounded structure 623 are integratedwith one another.

FIG. 18 illustrates an example process 1500 for controlling an outputtorque. At block 1502 of the process 1500, a rotary output shaft isprovided. For example, exemplary rotary output shafts are describedabove for actuating an elongate member (e.g., by actuating one or morepull wires of the elongate member).

At block 1504, at least one output motor is provided. For example, asdescribed above, exemplary output motors may be configured to actuatemovement of the elongate member by rotating the output shaft.

At block 1506, an output torque of the output shaft is detected ordetermined (e.g., based at least upon one sensor input). In an example,a load beam, load cell, or a torque sensor (e.g., as described above astorque sensor 616) may be employed. In examples where a load cell isemployed, the load cell may be configured to measure the output shafttorque based upon at least a deflection of the load cell. In an example,load cells may have a cantilever mounting within the instrument driver.In various embodiments, the output torque is detected or determinedutilizing a torque sensor assembly disposed around one or more of theprovided output shaft and output motor, as described above.

At block 1508, rotation of the output shaft may be modified (e.g., byadjusting one or more parameters of a motor or gearbox) based on theoutput torque. By modifying the rotation of the output shaft, tension ona pull wire coupled to the output shaft may be modified. Such a pullwire may be disposed within an elongate member. This may, for example,impart a bend or other motion to an articulating section of the elongatemember. In another example, modifying the output from the output shaftmay actuate a roller of an active drive system.

In one example embodiment of use for controlling output torque and/orcontrolling movement of an elongated member can include actuatingmovement of an elongated member by rotating an output shaft with amotor. Some embodiments can include detecting or determining outputtorque of the output shaft based at least in part upon on a sensorinput. For example, the sensor input can be based upon the torqueinduced strain along a torque sensor which can be disposed around one ormore of the output shaft or motor (e.g., as the reactive torque sensor616 described herein). The method can also include actuating the motorin response to the measured or determined output torque to drive theoutput shaft. The rotation of the output shaft 624 can be modified (e.g.by adjusting one or more parameters of a motor or gearbox) based on themeasured or determined output torque. The method of use can includemodifying tension on a pull wire or another element of the system bymodifying rotation of the output shaft in response to the measured ordetermined output torque. In some embodiments, the control system 113 isconfigured modify rotation of the output shaft in response to themeasured or determined output torque.

In various embodiments, by determining and selectively modifying theoutput torque (e.g., rotation of the output shaft), the output torquecan be carefully controlled. In some embodiments, this control enables arobotic catheter system to precisely and accurately tension one or morepull wires in an elongate member so that the resultant articulation ofthe elongate member precisely and accurately reflects the articulationcommanded by a user at an input device based on improved modeling ofpredicted catheter tip movement.

The exemplary systems and components described herein (e.g., workstation112, electronics rack 118, the control system 113, the exemplaryinstrument drivers, and/or any components thereof) may include acomputer or a computer readable storage medium or computer readablememory that has stored thereon executable instructions and there can beone or more processors in communication with the computer readablememory that are configured of execute the instructions to implement theoperation of drive and implement the various methods and processesdescribed herein. In general, computing systems and/or devices, such asuser input devices included in the workstation 112 and/or the controlsystem 113 or any components thereof, merely as examples, may employ anyof a number of computer operating systems, including, but by no meanslimited to, versions and/or varieties of the Microsoft Windows operatingsystem, the Unix operating system (e.g., the Solaris operating systemdistributed by Oracle Corporation of Redwood Shores, Calif.), the AIXUNIX operating system distributed by International Business Machines ofArmonk, N.Y., the Linux operating system, the Mac OS X and iOS operatingsystems distributed by Apple Inc. of Cupertino, Calif., and the Androidoperating system developed by the Open Handset Alliance.

Computing devices generally include computer-executable instructions,where the instructions may be executable by one or more computingdevices such as those listed above. Computer-executable instructions maybe compiled or interpreted from computer programs created using avariety of programming languages and/or technologies, including, withoutlimitation, and either alone or in combination, Java, C, C++, VisualBasic, Java Script, Perl, etc. In general, a processor (e.g., amicroprocessor) receives instructions, e.g., from a memory, acomputer-readable medium, etc., and executes these instructions, therebyperforming one or more processes, including one or more of the processesdescribed herein. Such instructions and other data may be stored andtransmitted using a variety of computer-readable media.

A computer-readable medium (also referred to as a processor-readablemedium or computer readable memory) includes any non-transitory (e.g.,tangible) medium that participates in providing data (e.g.,instructions) that may be read by a computer (e.g., by a processor of acomputer). Such a medium may take many forms, including, but not limitedto, non-volatile media and volatile media. Non-volatile media mayinclude, for example, optical or magnetic disks and other persistentmemory. Volatile media may include, for example, dynamic random accessmemory (DRAM), which typically constitutes a main memory. Suchinstructions may be transmitted by one or more transmission media,including coaxial cables, copper wire and fiber optics, including thewires that include a system bus coupled to a processor of a computer.Common forms of computer-readable media include, for example, a floppydisk, a flexible disk, hard disk, magnetic tape, any other magneticmedium, a CD-ROM, DVD, any other optical medium, punch cards, papertape, any other physical medium with patterns of holes, a RAM, a PROM,an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, or anyother medium from which a computer can read.

Databases, data repositories or other data stores described herein mayinclude various kinds of mechanisms for storing, accessing, andretrieving various kinds of data, including a hierarchical database, aset of files in a file system, an application database in a proprietaryformat, a relational database management system (RDBMS), etc. Each suchdata store is generally included within a computing device employing acomputer operating system such as one of those mentioned above, and areaccessed via a network in any one or more of a variety of manners. Afile system may be accessible from a computer operating system, and mayinclude files stored in various formats. An RDBMS generally employs theStructured Query Language (SQL) in addition to a language for creating,storing, editing, and executing stored procedures, such as the PL/SQLlanguage mentioned above.

In some examples, system elements may be implemented ascomputer-readable instructions (e.g., software) on one or more computingdevices (e.g., servers, personal computers, etc.), stored on computerreadable media associated therewith (e.g., disks, memories, etc.). Acomputer program product may have such instructions stored on computerreadable media for carrying out the functions described herein.

With regard to the processes, systems, methods, etc. described herein,it should be understood that, although the steps of such processes, etc.have been described as occurring according to a certain orderedsequence, such processes could be practiced with the described stepsperformed in an order other than the order described herein. It furthershould be understood that certain steps could be performedsimultaneously, that other steps could be added, or that certain stepsdescribed herein could be omitted. In other words, the descriptions ofprocesses herein are provided for the purpose of illustrating certainexamples, and should in no way be construed so as to limit the claims.

Accordingly, it is to be understood that the above description isintended to be illustrative and not restrictive. Many examples andapplications other than the examples provided would be apparent uponreading the above description. The scope should be determined, not withreference to the above description, but should instead be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled. It is anticipated andintended that future developments will occur in the technologiesdiscussed herein, and that the disclosed systems and methods will beincorporated into such future examples. In sum, it should be understoodthat the application is capable of modification and variation.

All terms used in the claims are intended to be given their broadestreasonable constructions and their ordinary meanings as understood bythose knowledgeable in the technologies described herein unless anexplicit indication to the contrary in made herein. In particular, useof the singular articles such as “a,” “the,” “said,” etc. should be readto recite one or more of the indicated elements unless a claim recitesan explicit limitation to the contrary.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various examples for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed embodiment. Thus the following claims arehereby incorporated into the Detailed Description, with each claimstanding on its own as a separately claimed subject matter.

1. A robotic surgical system, comprising: a control system configured tobe connected to an input device and to receive information forpositioning or orienting a catheter from the input device; and aninstrument driver operatively connected to the control system, theinstrument driver including: a motor configured to provide rotary outputto actuate movement of an elongate member; a gearbox configured tomodify the rotary output of the motor; and a reactive torque sensorcoaxial with and radially surrounding at least one of the motor and thegearbox, wherein the control system is configured to actuate the motorin response to the information to drive an output shaft in communicationwith the elongate member; and wherein the reactive torque sensor isconfigured to determine an output shaft torque imparted by the outputshaft.
 2. The robotic surgical system of claim 1, wherein the torquesensor does not substantially add to an overall length to the instrumentdriver along the longitudinal axis.
 3. The robotic surgical system ofclaim 1, wherein the reactive torque sensor provides a grounded mountingstructure for the motor and the gearbox.
 4. The robotic surgical systemof claim 1, wherein at least one of the gearbox and the rotary motor ismounted to the reactive torque sensor by a first mounting flange andwherein torque sensor is mounted to the instrument driver by a secondmounting flange.
 5. The robotic surgical system of claim 4, wherein atleast one of the first and second mounting flanges is integrally formedwith a wall of the motor or gearbox.
 6. The robotic surgical system ofclaim 4, wherein at least one strain gauge is placed on one or morestruts placed between the first mounting flange and the second mountingflange.
 7. The robotic surgical system of claim 6, wherein the at leastone strain gauge is configured to measure bending strain or shearstrain.
 8. The robotic surgical system of claim 7, wherein the firstmounting flange forms a first ring and the second mounting flange formsa second ring that is coaxial with the first ring.
 9. The roboticsurgical system of claim 8, wherein the one or more strut extends fromthe first ring to the second ring.
 10. The robotic surgical system ofclaim 1, wherein the instrument driver is configured to adjust apullwire tension to impart motion to a tip of the catheter.
 11. Therobotic surgical system of claim 1, wherein the reactive torque sensorfurther comprises at least one strain gauge configured to measure theoutput shaft torque.
 12. The robotic surgical system of claim 11,wherein the at least one strain gauge is placed on one or more strutsplaced between a first mounting flange and a second mounting flange. 13.The robotic surgical system of claim 12, wherein the at least one straingauge is configured to measure bending strain or shear strain.
 14. Therobotic surgical system of claim 1, comprising a grounded structure forsupporting the motor and gearbox and wherein the reactive torque systemcomprises a mounting flange that couples at least one of the motor orgear box to the grounded structure.
 15. An instrument driver for anelongate member of a robotic surgical system, comprising one or moredrive assemblies, each assembly comprising: a gearbox configured toactuate movement of the elongate member by driving an output shaft incommunication with the elongate member; a rotary output motor configuredto drive the gearbox; and a reactive torque sensor radially surroundingthe gearbox and configured to determine an output shaft torque impartedby the output shaft to the elongate member.
 16. The instrument driver ofclaim 15, wherein the torque sensor adds no axial length to the driveassembly.
 17. The instrument driver of claim 15, wherein the reactivetorque sensor provides a grounded mounting structure for the motor andthe gearbox.
 18. The instrument driver of claim 15, wherein the rotaryoutput motor is a brushless motor.
 19. The instrument driver of claim15, wherein at least one of the gearbox and the rotary motor is mountedto the reactive torque sensor by a first mounting flange and whereintorque sensor is mounted to the instrument driver by a second mountingflange.
 20. The instrument driver of claim 19, wherein the reactivetorque sensor further comprises at least one strain gauge configured tomeasure the output shaft torque. 21.-34. (canceled)